Magnetic resonance imaging, or MRI, is based on the nuclear spin properties of protons comprising different brain tissues. Through a remarkable set of engineering achievements, MRI is now routinely used to visualize the internal structure of the entire body, including the brain, in three dimensions. Perhaps even more impressively, the regional flow of blood in the brain, its relative proportion in a volume of gray matter, and its oxygenation level, can all be evaluated during sensory and behavioral tasks. The latter technique of functional MRI (fMRI) is now used by investigators in nearly every major university in the country and around the world to explore sensory processing, executive function, and social cognition. In just two decades, the fMRI revolution has brought the study of the human brain to the forefront of neuroscience, and has shaped the societal understanding of brain activity and its basis for all mental function and dysfunction. In the Neurophysiology Imaging Facility (NIF), we attempt to link this new field fMRI in humans to more detailed studies of brain physiology and anatomy in animals, since animal studies remain crucial for obtaining detailed information the structure and function of neural circuits that fMRI cannot obtain. The NIF is a centralized core facility that offers services to a wide range of investigators in each of the three sponsoring institutes (NIMH, NINDS, and NEI). Structural and functional imaging in the NIF exploit the latest cutting-edge imaging technology, allowing users to combine imaging with other invasive techniques, such as microelectrode recordings, pharmacological inactivation, or anatomical tract tracing. Testing animals inside a strong magnetic field has required the development of a wide array of MRI-compatible equipment, including animal chairs, restraint devices, reward delivery apparatus, eye position tracking cameras, and manual response keys. The facility thus provides users with these and other critical components of monkey fMRI, allowing them to initiate their studies with minimal development on their part. The facility staff assists investigators with experimental design, as well as the production of project-specific hardware (e.g. radiofrequency coils) that allow for optimized data collection. Using a standard setup developed over the last years, the facility typically carries out three scanning sessions per day, all in nonhuman primates. Some of sessions are devoted to high-resolution anatomical scanning, which allows investigators to determine the position of their electrodes, perform surgical planning, and evaluate the spread of pharmacological agents. In addition, the facility offers anatomical techniques, such as diffusion tensor imaging (DTI) and manganese tract tracing, which can be used in combination with electrophysiological studies or lesions. Most of the scans in the vertical scanner are aimed at evaluation of neural function. Typically fMRI scans are combined with an invasive procedure, such as reversible inactivation, cortical ablation, pharmacological manipulation, electrocorticogram recordings, electrical microstimulation, or recordings from chronic microwire arrays. The routine combination of fMRI and invasive techniques in awake, behaving monkeys makes the NIH Intramural Research Program a unique site to perform nonhuman primate research. NIH investigators that use the NIF core facility are studying a wide range of topics related to basic neurological function, motivation, decision-making, emotion, and depression.